Circuit breaker and control ambient temperature compensator including weakening slot adjusting means



March 1, 1966 M. T. LYBROOK 3,238,331

CIRCUIT BREAKER AND CONTROL AMBIENT TEMPERATURE COMPENSATOR INCLUDINGWEAKENING SLOT ADJUSTING MEANS 3 Sheets-Sheet 1 Filed Oct. 23, 1963 SPOTWELDED TOGETHER INVENTOR; MALCOLM T LYBROOK ATTORNEY March 1, 1966 TLYBROOK 3,238,331

CIRCUIT BREAKER AND CONTROL AMBIENT TEMPERATURE COMPENSATOR INCLUDINGWEAKENING SLOT ADJUSTING MEANS Filed Oct. 25, 1963 3 Sheets-Sheet 2INVENTOR, MALCOLM T LYBROOK ATTORNEY I 3,238,331 PENSA'IOR March 1966 M.T. LYBROOK CIRCUIT BREAKER AND CONTROL AMBIENT TEMPERATURE COM INCLUDINGWEAKENING SLOT ADJUSTING MEANS Filed Oct. 25, 1963 3 Sheets-Sheet 5INVENTOR.

MALCOLM 1'. LYBRO ATTORNE United States Patent 3,238,331 CIRCUIT BREAKERAND CONTROL AMBIENT TEMPERATURE COMPENSATOR INCLUDING WEAKENING SLOTADJUSTING MEANS Malcolm T. Lybrook, Frankfort, Ind., assignor to P. R.Mallory & Co., Inc., Indianapolis, Ind., a corporation of Delaware FiledOct. 23, 1963, Ser. No. 318,253 13 Claims. (Cl. 200114) This inventionrelates to electric controls and particularly to fast break snapswitches of the type usually found in radio and television receivers incombination with variable resistors, as well as other electricalapparatus. The present invention is a modification of the devicedescribed in application Serial No. 272,309, filed April 11, 1963,entitled Thermal Safe Power Switch for Controls.

As pointed out in assignees application Serial No. 272,309, the use offuses and other separate thermal safe devices, some of which areindependently mounted and actuated, is presently known and theaforementioned aplication provides a circuit breaker which tolerateslimited current fluctuations under ordinary circumstances while thepresent improvement allows for ambient temperature changes, keeping thecircuit closed during temporary current surges, the intensity of whichwould not be great enough to cause damage to components or the applianceitself.

Certain circuit breakers without ambient temperature compensationinherently have several undesirable operating characteristics forexample; any heat rise introduced into the bi-metal strip invariablyreduces contact pressure, and at times to the point where prematurecontact opening will occur; the slow displacement of the contact elementinduces contact welding or sticking and, of course, the possibility ofintermittent opening and closing of the contacts is ever present.

The present invention precludes these possibilities by means of acompensator which maintains contact pressure up to the instant ofopening. I have thus provided a resettable circuit breaker havingconsiderable advantage over the use of separate fuses and circuitbreakers as safety devices for example, the natural reaction to acessation of power to any appliance is to turn the unit off by meansprovided thereon whether it be a knob, push button, lever, etc. The actof opening the switch contacts in the present invention resets thecircuit breaker in preparation for a return to normal conditions.

It is therefore an object of the present invention to provide animproved snap switch for operation under fluctuating current conditions.

It is another object of the present invention to pro vide a new andnovel snap switch having an integral temperature responsive circuitbreaker which will not be falsely tripped or opened due to normalmomentary surges of current.

It is another object of the present invention to provide a circuitbreaker having a means for holding back the opening action of thecircuit breaker against a transient harmless overload.

It is still another object of the present invention to provide acombination snap switch and circuit breaker.

A further object of the present invention is to eliminate the need for aseparate fuse or circuit breaker in numerous electrical appliances.

A further object of the present invention is to provide a temperatureresponsive circuit breaker capable of being 3,238,331 Patented Mar. 1,1966 reset manually by normal manipulation of a control knob.

It is still a further object of the present invention to provide acircuit breaker which can be adjusted to various critical ranges ofthermal response.

It is still another object of the present invention to provide a compactpower switch and circuit breaker combination which is small in size andeconomical to manufacture.

Other objects will become apparent when the following description istaken in conjunction with the drawings in which:

FIG. 1 is a perspective view showing the general configuration of thepresent invention as it cooperates with a metal cup containing aninsulative rotor movably carrying a floating contact ring and anactuating projection for the present circuit breaker.

FIG. 2 is an exploded perspective view showing the cooperativerelationship of the component parts of the present invention.

FIG. 3 is a top view of the switch-circuit breaker assembly with the topof the upper chamber removed showing the components in the operating,current-carrying position.

FIG. 4 is the same as FIG. 3, except the bow spring, conductive leaf andbimental contact spring are shown as they would appear after a thermaloverload had been introduced placing the conductive leaf spring in acocked position for resetting.

FIGS. 5, 6, 7 and 8 represent typical applications for the presentinvention such as a push-push switch; a variable resistor in which theoperating shaft moves both radially, to regulate resistance, and axiallyto manipulate the switch and circuit breaker; a conventional rotaryswitch and a multi-plunger pushbutton switch.

Generally speaking, the basic unit consists of a housing of insulativematerial adapted to be attached to a circular cup containing a movablerotor which carries a floating ring type contact and an integralactuator for resetting a bimetal circuit breaker assembled in a cavityin the in sulative housing. The switch proper is manipulated manuallyfrom one position to another through an overcenter spring while thecircuit breaker only responds to a pre-determined thermal condition inone direction and is manually reset in the other direction. The circuitbreaker is capable of withstanding normal ambient temperatures as wellas brief current surges without opening the contacts or permittingcontact pressure to diminish until just prior to breaking. The housingprovides a base for the power switch contacts and a chamber on adifferent level for the overload mechanism. An adjustment is alsoprovided whereby the thermal resistance of the circuit breaker can beincreased or decreased depending on the temperature operating rangedesired.

Referring initially to FIGS. 1 and 2, there is shown at 10 a generallycircular housing made of insulating molding material carrying aplurality of wire connecting terminals 11 and 12 securely fastened to ahousing 10 by rivets 13 and 14. Terminal 12 is an integral part ofcontact frame 15 which serves as a carrier for circuit breaker assembly16 comprising a bow spring 17 and a bimetal spring 19 welded toconductive leaf spring 18 as shown at 26. Tab 21 of spring 18 is weldedto tab 22 of contact frame 15. The assembly consisting of bow spring 17,conductive leaf spring 18, bimetal contact spring 19 and contact frame15, is inserted into cavity 23 of housing 10 and secured thereto byrivet 14. An actuating tab 24 projects through aperture 25 of contactframe and is actuated into reset position by rotor projection 26, shownin FIG. 1. As described in application Serial No. 272,309, a three pointcontact is necessary to complete an active circuit. Therefore, whenterminal 11 and contact 27 are assembled to housing It by rivets 13 and28, a nest is formed to receive contact ring 29 shown in FIG. 1. A threepoint contact between terminal 11, terminal 12 and contact 27, completesthe circuit with two terminations. A weakening slot 30 is provided incontact frame 15 in order that the bow spring pivot arm 31 may beadjusted to increase or decrease the mechanical stress of the bimetalleaf thereby changing the range of currents to be tolerated by thecircuit breaker.

Contact frame 15 is prevented from rotating around rivet 14 whenaperture 32 is assembled over projection 33 extending above the surface34 of housing 10.

As can be more clearly seen in FIG. 3 (normal on position), a livecircuit is formed through contact frame 15 and integral terminal 12,contact ring '29, terminal 11 and contact 27. When an overload currentis introduced, circuit breaker assembly 16 snaps into open position asshown by solid lines in FIG. 4, thereby isolating terminal 11, contactring 29 and contact 27 for which there is no wire connection. When theappliance is turned off, as indicated by the arrow in FIG. 4, contactring 29 opens the connection between contact 27 and terminal 11, cuttingoif the power supply and at the same time resetting the circuit breakerin preparation for a return to normal conditions when reversemanipulation of the switch shaft to the on position places the rotorprojection back to the position shown in FIG. 3. Until a subsequentoverload is again encountered the projection is ineffective in bothpositions.

While I have described a single embodiment of the present invention, itis to be understood that modifiications may be made without departingfrom the spirit thereof. I claim as my invention:

1. In a combination an electric switch and overload mechanism adjustableso as to respond to a particular overload current of a plurality ofoverload currents comprising: a housing carrying a plurality ofterminals; a first level formed within said housing; a means carrying acontact ring and mounted within said first level, said rotor means foractuating said ring from a disengaged position to an engaged positionwith said terminals so as to allow current to pass therethrough; and asecond level formed in said housing, said second level including anadjustable contact frame means containing a weakening slot for mountingan overcenter snap action circuit breaker means, the position of saidadjustable contact frame determinative of said overload current of saidrange of overload currents, said circuit breaker means including acontact carrying bimetal spring means having a contact carrying endnormally biased into engagement with one of said terminals, said contactremaining in engagement with said one terminal as an initial flow ofsaid overload current flows therethrough, continued flow of saidoverload current displacing said circuit breaker means so as to storeenergy therein, said circuit breaker means releasing said stored energyafter said overcenter condition is exceeded thereby displacing saidcontact of said bimetal spring from said engaged position with said oneterminal with a snap action motion.

I 2. In combination an electric switch and overload mechanism responsiveto an overload current of a range of overload currents comprising: ahousing carrying a plurality of terminals; a first level formed withinsaid housing; a means carrying a contact ring and mounted within saidfirst level, said means for actuating said ring from a disengagedposition to an engaged position with said terminals so as to allowcurrent to pass therethrough; a second level formed in said housing,said second level including an adjustable contact frame means containinga weakening slot for pivotally mounting an overcenter snap actioncircuit breaker means, the position of said adjustable contact framedeterminative of said overload current of said range of overloadcurrents, said circuit breaker means including a contact carryingbimetal spring means having a contact carrying end normally biased intoengagement with one of said terminals, said contact remaining inengagement with said one terminal as an initial flow of said overloadcurrent flows therethrough, continued flow of said overload currentdisplacing said circuit breaker means so as to store energy therein,said circuit breaker means releasing said stored energy after saidovercenter condition is exceeded thereby displacing said contact of saidbimetal spring from said engaged position with said one terminal with asnap action motion; and means for resetting said circuit breaker means,said circuit breaker means resettable only when said ring is disengagedfrom said terminals.

3. In combination an electric switch and overload mechanism adjustableso as to respond to a particular overload current of a plurality ofoverload currents comprising: a housing carrying a plurality ofterminals; a first level formed within said housing; a means carrying acontact ring and mounted within said first level, said means foractuating said ring from a disengaged position to an engaged positionwith said terminals so as to allow current to pass therethrough; asecond level formed in said housing, said second level including anadjustable contact frame means for pivotally mounting an overcenter snapaction circuit breaker means, said adjustable contact frame including aslot whose width is determinative of said overload current of saidplurality of overload currents, said circuit breaker means including acontact carrying bimetal spring means having a contact carrying endnormally biased into engagement with one of said terminals, said contactremaining in engagement with said one terminal as an initial flow ofsaid overload current flows therethrough, continued flow of saidoverload current displacing said circuit breaker means so as to storeenergy therein, said circuit breaker means releasing said stored energyafter said overcenter condition is exceeded thereby displacing saidcontact of said bimetal spring from said engaged position with said Oneterminal with a snap action motion; and means for resetting said circuitbreaker means, said circuit breaker means resettable only when said ringis disengaged from said terminals.

4. In combination an electric switch and overload mechanism responsiveto an overload current of a range of overload currents comprising: ahousing carrying a plurality of terminals; a first level formed withinsaid housing; a means carrying a contact ring and mounted Within saidfirst level, said rotor means for actuating said ring from a disengagedposition to an engaged position with said terminals so as to allowcurrent to pass therethrough; a second level formed in said housing,said second level including an adjustable contact frame means forpivotally mounting an overcenter snap action circuit breaker means, saidadjustable contact frame including a slot whose width is determinativeof the longitudinal compression under which said circuit breaker meansis mounted, said circuit breaker means including a contact carryingbimetal spring means having a contact carrying end normally biased intoengagement with one of said terminals, said contact remaining inengagement with said one terminal as an initial overload current flowstherethrough, continued flow of said overload current displacmg saidcircuit breaker means so as to store energy therein, said circuitbreaker means releasing said stored energy after said overcentercondition is exceeded thereby displacing said contact of said bimetalspring from said engaged position with said one terminal with a snapaction motion; and means for resetting said circuit breaker means, saidcircuit breaker means resettable only when said ring is disengaged fromsaid terminals.

5. In combination an electric switch and overload 'mechanism adjustableso as to respond to a particular overload current of a plurality ofoverload currents comprising: a housing having a base, said basecarrying a plurality of terminals; a first level formed within saidhousing by said base; a rotor means carrying a floating contact ring andmounted within said first level, said rotor means for actuating saidring from a disengaged position to an engaged position with saidterminals so as to allow current to pass therethrough; a second levelformed in said base, said second level including an adjustable contactframe means for pivotally mounting an overcenter snap action circuitbreaker means, said adjustable contact frame including a slot whosewidth is determinative of the longitudinal compression under which saidcircuit breaker means is mounted, said circuit breaker means including acontact carrying bimetal spring means having a free contact carrying endnormally biased into engagement with one of said terminals, said contactremaining in engagement with said one terminal as an initial overloadcurrent flows therethrough, continued fiow of said overload currentdisplacing said circuit breaker means so as to store energy therein,said circuit breaker means releasing said stored energy after saidovercenter condition is exceeded thereby displacing said contact of saidbimetal spring from said engaged position with said one terminal with asnap action motion; and means for resetting said circuit breaker means,said circuit breaker means resettable only when said ring is disengagedfrom said terminals.

6. In combination an electric switch and overload mechanism adjustableso as to respond to a particular overload current of a plurality ofoverload currents comprising: a housing having a base, said basecarrying a plurality of terminals; a first level formed within saidhousing by said base; a rotor means carrying a floating contact ring andmounted within said first level, said rotor means for actuating saidring from a disengaged position to an engaged position with saidterminals so as to allow current to pass therethrough; a second levelformed in said base, said second level including an adjustable contactframe means for pivotally mounting an overcenter snap action circuitbreaker means, said adjustable contact frame including a slot whoseWidth is determinative of the longitudinal compression under which saidcircuit breaker means is mounted, said circuit breaker means including acontact carrying bimetal spring means having a free contact carrying endnormally biased into engagement with one of said terminals, said contactremaining in engagement with said one terminal as an initial flow ofsaid overload current flows therethrough, continued flow of saidoverload current displacing said circuit breaker means so as to storeenergy therein, and increasing the contact pressure exerted by saidcontact carrying bimetal spring against said one terminal, said circuitbreaker means releasing said stored energy after said overcentercondition is exceeded thereby displacing said contact of said bimetalspring from said engaged position with said one terminal with a snapaction motion; and means for resetting said circuit breaker means, saidcircuit breaker means resettable only when said ring is disengaged fromsaid terminals.

7. In combination an electric switch and overload mechanism comprising:a housing carrying a plurality of terminals; a first level formed withinsaid housing; means carrying a contact ring and mounted within saidfirst level, said rotor means for actuating said ring from a disengagedposition to an engaged position with said terminals so as to allowcurrent to pass therethrough; and a second level formed in said housing,said second level including an adjustable means containing a weakeningslot for mounting an overcenter snap action circuit breaker means, saidcircuit breaker means including a leaf spring means having an endcoupled to said mounting means, a contact carrying bimetal spring meanshaving one end coupled to said leaf spring, said bimetal springextending angularly with respect to said leaf spring to normally biassaid contact into engagement with one of said terminals, a bowed springhaving one extremity coupled to the other end of said leaf spring andsaid other extremity of said bowed spring coupled to said mountingmeans, said contact of said bimetal spring remaining in engagement withsaid one terminal as in initial overload current flows therethrough,continued flow of said overload current straightening said bimetalspring thereby displacing said leaf spring and said bowed spring so asto store energy in said bowed spring, said bowed spring releasing saidstored energy after said overcenter condition is exceeded so as todisplace said contact of said bimetal spring from said engaged posit-ionwith said one terminal with a snap action motion.

'8. In combination an electric switch and overload mechanism adjustableso as to respond to a particular overload current of a plurality ofoverload currents comprising: a housing carrying a plurality ofterminals; a first level formed within said housing, a means carrying acontact ring and mounted within said first level, said rotor means foractuating said ring from a disengaged position to an engaged positionwith said terminals so as to allow current to pass therethrough; and asecond level formed in said housing, said second level includmg anadjustable contact frame means containing a weakening slot for mountingan overcenter snap action circuit breaker means, the position of saidadjustable contact frame determinative of said overload current of saidrange of overload currents, said circuit breaker means including a leafspring means having an end coupled to said mounting means, a contactcarrying bimetal spring means having one end coupled to said leafspring, said bimetal spring extending angularly with respect to saidleaf spring to normally bias said contact into engagement with one ofsaid terminals, a bowed spring having one extremity coupled to the otherend of said leaf spring and said other extremity of said bowed springcoupled to said mounting means, said contact of said bimetal springremaining in engagement with said one terminal as an initial overloadcurrent flows therethrough, contmued fiow of said overload currentstraightening said bimetal spring thereby displacing said leaf springand said bowed spring so as to store energy in said bowed sp-rmg, saidbowed spring releasing said stored energy after said overcentercondition is exceeded so as to displace said contact of said bimetalspring from said engaged position with said one terminal with a snapaction motion.

9. In combination an electric switch and overload mechanism responsiveto an overload current of a range of overload currents comprising: ahousing carrying a plurality of terminals; a first level formed withinsaid housing; a means carrying a contact ring and mounted with saidfirst level, said means for actuating said ring from a disengagedposition to an engaged position with said terminals so as to allowcurrent to pass therethrough; a second level formed in said housing,said second level including an adjustable contact frame means containinga weakening slot for pivotally mounting an overcenter snap actioncircuit breaker means, the position of said adjustable contact framedeterminative of said overload current of said range of overloadcurrents, said circuit breaker means including a leaf spring meanshaving an end coupled to said mounting means, a contact carrying bimetalspring means having one end coupled to said leaf spring, said bimetalspring extending angularly with respect to said leaf spring to normallybias said contact into engagement with one of said terminals, a bowedspring having one extremity pivotally coupled to the other end of saidleaf spring and said other extremity of said bowed spring pivotallycoupled to said mounting means, said contact of said bimetal springremaining in engagement with said one terminal as an initial flow ofsaid overload current flows therethrough, continued flow of saidoverload current straightening said bimetal spring thereby displacingsaid leaf spring and said bowed spring so as to store energy in saidbowed spring, said bowed spring releasing said stored energy after saidovercenter condition is exceeded so as to displace said contact of saidbimetal spring from said engaged position with said one terminal with asnap action motion; and means for resetting said circuit breaker means,said circuit breaker means resettable only when said ring is disengagedfrom said terminals.

10. In combination an electric switch and overload mechanism adjustableso as to respond to a particular overload current of a plurality ofoverload currents comprising: a housing carrying a plurality ofterminals; a first level formed within said housing; a means carrying acontact ring and mounted within said first level, said means foractuating said ring from a disengaged position to an engaged positionwith said terminals so as to allow current to pass therethrough; asecond level formed in said housing, said second level including anadjustable contact frame means for pivotally mounting an overcenter snapaction circuit breaker means, said adjustable contact frame including aslot whose width is determinative of said overload current of saidplurality of overload currents, said circuit breaker means including aleaf spring means having an end coupled to said mounting means, acontact carrying bimetal spring means having one end coupled to saidleaf spring, said bimetal spring extending angularly with respect tosaid leaf spring to normally bias said contact into engagement with oneof said terminals, a bowed spring having one extremity pivotally coupledto the other end of said leaf spring and said other extremity of saidbowed spring pivotally coupled to said mounting means, said contact ofsaid bimetal spring remaining in engagement with said one terminal as aninitial flow of said overload current flows therethrough, continued flowof said overload current straightening said bimetal spring therebydisplacing said leaf spring and said bowed spring so as to store energyin said bowed spring, said bowed spring releasing said stored energyafter said overcenter condition is exceeded so as to displace saidcontact of said bimetal spring from said engaged position with said oneterminal with a snap action motion; and means for resetting said circuitbreaker means, said circuit breaker means resettable only when said ringis disengaged from said terminals.

11. In combination an electric switch and overload responsive to anoverload current of a range of overload currents mechanism comprising: ahousing carrying carrying a plurality of terminals; a first level formedwith-in said housing; a means carrying a contact ring and mounted withinsaid first level, said rotor means for actuating said ring from adisengaged position to an engaged position with said terminals so as toallow current to pass therethrough; a second level formed in saidhousing, said second level including an adjustable contact frame meansfor pivotally mounting an overcenter snap action circuit breaker means,said adjustable contact frame including a slot whose width isdeterminative of the longitudinal compression under which said circuitbreaker means is mounted, said circuit breaker means including a leafspring means having an end coupled to said mounting means, a contactcarrying bimetal spring means having one end coupled to said leafspring, said bimetal spring extending angularly with respect to saidleaf spring to normally bias said contact into engagement with one ofsaid terminals, a bowed spring having one extremity pivotally coupled tothe other end of said leaf spring and said other extremity of said bowedspring pivotally coupled to said mounting means, said contact of saidbimetal spring remaining in engagement with said one terminal as aninitial overload current flows therethrough, continued fiow of saidoverload current straightening said bimetal spring thereby displacingsaid leaf spring and said bowed spring so as to store energy in saidbowed spring,

said bowed spring releasing said stored energy after said overcentercondition is exceeded so as to displace said contact of said bimetalspring from said engaged position with said one terminal with a snapaction motion; and means for resetting said circuit breaker means, saidcircuit breaker means resettable only when said ring is disengaged fromsaid terminals.

12. In combination an electric switch and overload mechanism adjustableso as to respond to a particular overload current of a plurality ofoverload currents comprising: a housing having a base, said basecarrying a plurality of terminals; a first level formed within saidhousing by said base; a rotor means carrying a floating contact ring andmounted within said first level, said rotor means for actuating saidring from a disengaged position to an engaged position with saidterminals so as to allow current to pass thcrethrough; a second levelformed in said base, said level including an adjustable contact framemeans for pivotally mounting an overcenter snap action circuit breakermeans, said adjustable contact frame in cluding a slot, whose width isdeterminative of the longitudinal compression under which said circuitbreaker means is mounted, said circuit breaker means including a leafspring means having an end coupled to said mounting means, a contactcarrying bimetal spring means having one end coupled to said leafspring, said bimetal spring extending angularly with respect to saidleaf spring to normally bias said contact into engagement with one ofsaid terminals, a bowed spring having one extremity pivotally coupled tothe other end of said leaf spring and said other extremity of said bowedspring pivotally coupled to said mounting means, said contact of saidbimetal spring remaining in engagement with said one terminal as aninitial overload current flows therethrough, continued flow of saidoverload current straightening said bimetal spring thereby displacingsaid leaf spring and said bowed spring so as to store energy in saidbowed spring, said bowed spring releasing said stored energy after saidovercenter condition is exceeded so as to displace said contact of saidbimetal spring from said engaged position with said one terminal with asnap action motion; and means for resetting said circuit breaker means,said circuit breaker means resettable only when said ring is disengagedfrom said terminals.

13. In combination an electric switch and overload mechanism adjustableso as to respond to a particular overload current of a plurality ofoverload currents comprising: a housing having a base, said basecarrying a plurality of terminals; a first level formed within saidhousing by said base; a rotor means carrying a floating contact ring andmounted within said first level, said rotor means for actuating saidring from a disengaged position to an engaged position with saidterminals so as to allow current to pass therethrough; a second levelformed in said base, said second level including an adjustable contactframe means for pivotally mounting an overcenter snap action circuitbreaker means, said adjustable contact frame including a slot whosewidth is determinative of the longitudinal compression under which saidcircuit breaker means is mounted, said circuit breaker means including aleaf spring means having an end coupled to said mounting means, acontact carrying bimetal spring meas having one end coupled to said leafspring, said bimetal spring extending angularly with respect to saidleaf spring to normally bias said contact into engagement with one ofsaid terminals, a bowed spring having one extremity pivotally coupled tothe other end of said leaf spring and said other extremity of said bowedspring pivotally coupled to said mounting means, said contact of saidbimetal spring remaining in engagement with said one terminal as ainitial flow of said overload current flows therethrough, continued flowof said overload current straightening said bimetal spring therebydisplacing said leaf spring and said bowed spring so as to store energyin said bowed spring and increasing the contact pressure exerted by saidcontact carrying bimetal spring against said one terminal, said bowedspring releasing said stored energy after said overcenter condition isexceeded so as to displace said contact of said bimetal spring from saidengaged position with said one terminal with a snap action motion; andmeans for resetting said circuit breaker means, said circuit breakermeans resettable only when said ring is disengaged from said terminals.

References Cited by the Examiner UNITED STATES PATENTS 2,275,893 3/1942Ettinger 200139 2,521,120 9/1950 Harrold 20067 2,611,845 9/1952 Miller20067 BERNARD A. GILHEANY, Primary Examiner. H. A. LEWITTER, AssistantExaminer.

1. IN A COMBINATION AN ELECTRIC SWITCH AND OVERLOAD MECHANISM ADJUSTABLESO AS TO RESPOND TO A PARTICULAR OVERLOAD CURRENT OF A PLURALITY OFOVERLOAD CURRENTS COMPRISING: A HOUSING CARRYING A PLURALITY OFTERMINALS; A FIRST LEVEL FORMED WITHIN SAID HOUSING; A MEANS CARRYING ACONTACT RING AND MOUNTED WITHIN SAID FIRST LEVEL, SAID ROTOR MEANS FORACTUATING SAID RING FROM A DISENGAGED POSITION TO AN ENGAGED POSITIONWITH SAID TERMINALS SO AS TO ALLOW CURRENT TO PASS THERETHROUGH; AND ASECOND LEVEL FORMED IN SAID HOUSING, SAID SECOND LEVEL INCLUDING ANADJUSTABLE CONTACT FRAME MEANS CONTAINING A WEAKENING SLOT FOR MOUNTINGAN OVERCENTER SNAP ACTION CIRCUIT BREAKER MEANS, THE POSITION OF SAIDADJUSTABLE CONTACT FRAME DETERMINATIVE OF SAID OVERLOAD CURRENT OF SAIDRANGE OF OVERLOAD CURRENTS, SAID CIRCUIT BREAKER MEANS INCLUDING ACONTACTING CARRYING BIMETAL SPRING MEANS HAVING A